Ceramics have several advantages over other materials in MEMS, such as heat resistance, hardness, corrosion resistivity even in harsh environments, chemical inertness for biological applications and catalytic activity of surfaces and so on. For these advantages ceramic microstructures will be very potentially useful in microsystem, especially in microreactor. A novel method for the high aspect ratio micro ceramic structures fabrication based on deep X-ray lithography and lost-mold technique is developed. By using this method, ceramic microreactors have been successfully fabricated. The ceramic microreactor consists of 14 identical microchannels in parallel, each with typical dimensions of approximately 300 μm in width, 400 μm in height and 20 mm in length. The Ni film catalyst with thickness of 300 nm is uniformly coated through sputtering process. The steam reforming of Ethanol into hydrogen on the ceramics microreactor was studied at temperatures between 500 and 700°C. The microreactors have been characterized by studying of C2H6O conversion, H2 selectivity, and product stream composition.